OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What happens during stage 3 of a baby's growth?

1. The embryo starts to differentiate into specific tissues

2. The zygote divides into a ball of identical cells

3. The zygote implants into the uterus

4. The cells form the first organs

The correct answer is: The zygote divides into a ball of identical cells

During stage 3 of a baby's growth, the accurate description focuses on the critical process of organ formation. By this stage, significant development has already taken place, leading to the development of the first organs in the embryo. At this point in embryonic development, the cells that were previously dividing rapidly and differentiating begin to organize into specific structures that will ultimately form vital organs. This process is crucial because it lays the foundation for the complex systems that will sustain life after birth. While the other options describe essential steps in early development—such as the zygote dividing into a blastocyst or implanting into the uterus—stage 3 specifically highlights the transition from cellular division and differentiation into the formation of functional organs.